Resin composite and method for producing resin composite

Abstract

This resin composite comprises a thermoplastic resin and cellulose fibers, wherein a raw material of the main component of the cellulose fibers is low-basis-weight paper having a basis weight of 100 g / m2 or lower after undergoing a drying step.

Description

Resin composite and method for producing the resin composite

[0001] The present invention relates to a resin composite and a method for making a resin composite.

[0002] In resin composites, there is a trade-off between mechanical strength (flexural modulus, flexural strength) and impact strength, and various studies have been conducted to resolve this trade-off (see, for example, Patent Documents 1 to 3). Patent Documents 1 and 2 discuss resin composites containing inorganic fillers, and Patent Document 3 discusses resin composites containing reinforcing fibers, but further performance improvements are required. Furthermore, while the linear expansion coefficient is an important index for imparting dimensional stability in the molding of thermoplastic resins, a resin composite that is excellent in all of mechanical strength, impact strength, and linear expansion coefficient, and a method for producing the same have not yet been established.

[0003] Patent Document 1: JP 2009-62492 A, International Publication No. 2018 / 135648, International Publication No. 2019 / 208826

[0004] An object of the present invention is to provide a resin composite having excellent mechanical strength, impact strength, and linear expansion coefficient, and a method for producing the resin composite.

[0005] As a result of extensive research, the inventors discovered that the above object can be achieved by using low basis weight paper that has been dried, particularly household thin paper products such as toilet paper, tissue paper, and wipers, and thus completed the present invention. Specifically, a resin composite obtained by heat-kneading cellulose fibers obtained from low basis weight paper that has been dried with a thermoplastic resin exhibits excellent mechanical strength (flexural modulus and flexural strength), impact strength, and linear expansion coefficient.

[0006] That is, according to the present invention, (1) a resin composite containing a thermoplastic resin and cellulose fibers, wherein the raw material of the main component of the cellulose fibers has a basis weight of 100 g / m2 after being subjected to a drying process. ２(2) The resin composite which is a low basis weight paper as follows: (2) The resin composite according to (1), characterized in that the cellulose fibers are pulverized products that have been subjected to a pulverization process; (3) The resin composite according to (1) or (2), characterized in that the cellulose fibers are pulverized products having a loose bulk density in the range of 10 to 60 g / L; (4) The resin composite according to (1) or (2), characterized in that the cellulose fibers are pulverized products having a hard bulk density in the range of 15 to 80 g / L; (5) The resin composite according to (1) or (2), characterized in that the aspect ratio retention rate of the cellulose fibers, expressed as (aspect ratio of cellulose fibers in pulverized product) / (aspect ratio of cellulose fibers before pulverization process) × 100 (%), is 60% or more; (6) The resin composite according to (1) or (2), characterized in that the low basis weight paper has a basis weight of 3 to 40 g / m ２ (7) The resin composite according to (1) or (2), wherein the low basis weight paper is household tissue paper; (8) The thermoplastic resin is a polyolefin or a blend of a polyolefin and an elastomer, and has a flexural modulus of 1.00 GPa or more and an impact strength of 5.0 kJ / m ２ or more, and the linear expansion coefficient is 100×10 －６ (9) The resin composite according to (1) or (2), characterized in that the thermoplastic resin has an impact strength of 3.0 kJ / m or less. ２ (10) The resin composite according to (1) or (2), wherein the thermoplastic resin is nylon or a blend of nylon and elastomer, and has a flexural modulus of elasticity of 1.60 GPa or more and an impact strength of 2.0 kJ / m or more. ２ or more, and the linear expansion coefficient is 70 × 10 －６ (11) The resin composite according to (1) or (2), characterized in that the thermoplastic resin has an impact strength of 3.0 kJ / m or less. ２ (12) The thermoplastic resin is a polylactic acid or a blend of polylactic acid and an elastomer, and has a flexural modulus of 3.50 GPa or more and an impact strength of 3.0 kJ / m or more.２ or more, and the linear expansion coefficient is 80×10 －６ (13) A method for producing a resin composite, comprising the following steps (A) to (C): Step (A): subjecting raw pulp to a papermaking step and a drying step, and having a basis weight of 100 g / m ２ A process for obtaining the following low basis weight paper: Step (B): A process for pulverizing the low basis weight paper that has been subjected to the step (A); Step (C): A process for mixing the low basis weight paper pulverized in the step (B) with a thermoplastic resin, and kneading the mixture under heat. (14) A method for producing a resin composite according to (13), characterized in that the step (B) is performed to pulverize the low basis weight paper so that the loose bulk density of the low basis weight paper is in the range of 10 to 60 g / L; (15) A method for producing a resin composite according to (13) or (14), characterized in that the step (B) is performed to pulverize the low basis weight paper so that the hard bulk density of the low basis weight paper is in the range of 15 to 80 g / L; (16) The method for producing a resin composite according to (13) or (14) is provided, characterized in that the step (B) is performed so that the aspect ratio retention rate, expressed as (aspect ratio of the pulverized low basis weight paper) / (aspect ratio of the low basis weight paper before the pulverization step) × 100 (%), is 60% or more.

[0007] According to the present invention, it is possible to provide a resin composite having excellent mechanical strength (flexural modulus, flexural strength), impact strength, and linear expansion coefficient, and a method for producing the resin composite.

[0008] The resin composite of the present invention and a method for producing the resin composite are described below. The resin composite of the present invention is a resin composite containing a thermoplastic resin and cellulose fibers, and the cellulose fibers are a main component of the resin composite that has a basis weight of 100 g / m2 after a drying process. ２ The following low basis weight papers are used as raw materials:

[0009] The method for producing a resin composite of the present invention is characterized by comprising the following steps (A) to (C): Step (A): subjecting raw pulp to a papermaking step and a drying step, and producing a paper having a basis weight of 100 g / m ２The following steps are performed to obtain low basis weight paper: Step (B): A step of pulverizing the low basis weight paper that has been subjected to step (A); Step (C): A step of mixing the low basis weight paper pulverized in step (B) with a thermoplastic resin, and kneading the mixture under heating.

[0010] (Cellulose Fiber) The cellulose fiber used in the present invention is obtained from low basis weight paper, the main component of which has been subjected to a drying process. In the present invention, the low basis weight paper that has been subjected to the drying process may then be hydrolytically crushed.

[0011] In the present invention, low-basis weight paper that has been subjected to a drying process is used. ２ The following low-basis weight paper is used. Paper production generally involves high-speed, efficient papermaking processes, such as papermaking and coating, followed by multiple, powerful drying steps. Paper that has undergone these processes is likely to have stiff fibers with relatively many hydrogen bond points between cellulose fibers. In contrast, low-basis weight paper is often produced at a relatively slow speed to prevent paper breaks, which allows for the production of cellulose fibers with few hydrogen bond points and easy dispersibility. It is believed that the inclusion of such fibers facilitates dispersion of the fibers in the resin composite while maintaining their elongated, high aspect ratio, thereby increasing mechanical strength. In the present invention, it has been discovered that using such low-basis weight paper to form a resin composite can partially solve the problem.

[0012] The method for producing these low basis weight papers is not particularly limited, but can be achieved by passing a papermaking raw material containing a predetermined concentration of plant fibers through a fourdrinier, short wire, or round wire net to produce a web (wet paper), dewatering the web by squeezing, and then drying it in various known drying devices. The web may then be wound onto a reel for production. Examples of such papers include printing papers such as tissue paper, newsprint, fine paper, medium-quality paper, and wood-bleaching paper; processing papers such as packaging paper, moisture-proof paper, wallpaper lining paper, paper container base paper, laminated board base paper, and base paper for molding; inkjet recording paper, thermal recording paper, pressure-sensitive recording paper, lightly coated papers such as art paper; form paper; and cardboard base paper. However, to suppress agglomerations in the resin composite, papers without a coating layer or lamination are preferred. These papers have a basis weight of 100 g / m ２Any of the following may be used without particular limitation, and for example, commercially available products may be used.

[0013] Furthermore, it was found that the effect was enhanced by using thin paper, which has a particularly low basis weight among the low basis weight papers mentioned above. According to the Paper and Pulp Handbook (published in 1971), thin paper is a general term for thin paper, and has a basis weight of 40 g / m². ２ The basis weight of tissue paper is set to be less than the above-mentioned papers. Tissue paper has an even lower basis weight than the above-mentioned papers, and if foreign matter or impurities are present in the pulp, the paper breaks and becomes difficult to make. It is also known that if pulp-derived aggregates are present in the resin composite, they can trigger cracks that occur during strength tests and reduce impact strength. Since tissue paper is a low basis weight paper, it is preferable to produce it with minimal foreign matter or impurities or aggregates in its production, and it is therefore suitable for the present invention. However, if the basis weight is too low, handling during papermaking becomes poor, so it is set to be 3 to 40 g / m ２ It is preferable that the density is 5 to 30 g / m ２ It is more preferable that:

[0014] Specific examples of tissue paper that can be used include household tissue paper, glassine paper, rice paper, India paper, carbon paper base paper, office tissue paper, condenser paper, carbonless base paper, carbon-backed base paper, pressure-sensitive paper, foil paper, backing paper, insulating paper, release paper, cap body base paper, paper cloth base paper, weaving base paper, noodle band paper, rayon refined paper, fruit wrapping paper, transfer paper, drawing paper base paper, airmail paper, artificial flower base paper, mizuhiki base paper, motoyui base paper, Tengujo paper, gampi paper, Kyoto paper for wrapping tissues, tea bag paper, etc. Of these, household tissue paper is more preferable because it contains fewer chemicals, fillers, and impurities that are mixed in during the pulp and papermaking processes. Household thin papers include tissue paper, toilet paper, wipes, tissue paper, towel paper, napkin paper, table napkin paper, tempura paper, sheet paper, pillowcase paper, diaper paper, diaper paper, dress paper, etc. Toilet paper, tissue paper, and wipes are particularly preferred because they use small amounts of chemicals and fillers and are subject to strict hygiene controls to prevent the inclusion of foreign matter and impurities, with toilet paper being particularly preferred.

[0015] The toilet paper preferably conforms to the standard of JIS P4501:2006, and in particular has a basis weight of 18 g / m when measured in accordance with the standard. ２ It is preferable that the burst strength is 78 kPa or more, and the ease of disintegration is 100 seconds or less.

[0016] The raw materials for the paper used in the present invention can be, and are preferably, wood-based virgin pulps such as softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), or softwood unbleached kraft pulp (NUKP), or recycled waste paper pulp. In addition to the above, wood pulp derived from softwoods or hardwoods can also be used. Non-wood plant-derived pulps include straw pulp, bagasse pulp, reed pulp, kenaf pulp, linen pulp, ramie pulp, hemp pulp, flax pulp, and bamboo pulp. In the present invention, the pulp may or may not contain lignin. A lignin-removal process may be performed during the manufacturing process, or a lignocellulosic fiber may be treated to remove lignin. Plant-derived fibers that do not originally contain lignin can also be used. Furthermore, for example, dissolving pulp, sulfite pulp, kraft pulp, semi-chemical pulp, chemi-ground pulp, refiner ground pulp, thermomechanical pulp, groundwood pulp, refiner ground pulp, thermomechanical pulp, and pulp for fiberboard may be used. Using these pulps, low basis weight paper can be obtained through the papermaking process and drying process, and the above pulps may be used alone or in combination.

[0017] The type and blending ratio of these pulps can be adjusted or changed to suit the quality required for various types of paper. Furthermore, various chemicals may be added (internal addition) to achieve the required quality and operational stability. Examples of such chemicals include softeners, bulking agents, dyes, dispersants, wet strength agents, dry strength agents, drainage aids, pitch control agents, and retention aids. These pulps may also be bleached, and intermediate products that have undergone the drying process during manufacturing, such as broke paper and recycled paper, may also be used.

[0018] Low basis weight paper according to the present invention can be manufactured by a known papermaking method. An example is described below, but this is not limiting. First, papermaking raw materials are supplied from a raw material tank and further diluted with white water to prepare a stock. This stock is degassed, screened, and then sent to the stock inlet by a fan pump. The stock inlet supplies the stock onto the wire at an appropriate consistency, speed, and angle, ensuring that the stock is uniform across the entire width of the wire, is free of flocs (small lumps), and the fibers are well dispersed to prevent flow stripes. The stock inlet can be a headbox installed at an elevated location and open to the atmosphere, or a pressurized or hydraulic type, and any of these may be used. The stock is then jetted from the stock inlet between the wire and felt, forming a sheet (web, wet paper) onto the felt.

[0019] The web formed between the wire and felt is transferred to a Yankee dryer in close contact with the pressure roll. The web is then dried by a Yankee dryer and Yankee dryer hood, and then creped by a creping doctor before being peeled off the Yankee dryer and wound onto a reel via a reel drum. The Yankee dryer is a cast iron or cast steel drum used to dry the web, typically with an outer diameter of 2.4 to 6 m. Creping is a method of mechanically compressing paper in the machine direction (machine running direction) to form wavy wrinkles called crepes. It is used to impart bulk, softness, absorbency, surface smoothness, and aesthetic appearance (crepe shape) to low-basis weight paper, particularly thin paper such as toilet paper and tissue paper. The crepe is then formed by the creping doctor due to the speed difference between the Yankee dryer and the reel (reel speed ≦ Yankee dryer speed). The crepe characteristics depend on the speed difference, but the basis weight of the base paper on the Yankee dryer is 7 to 40 g / m ２ In this case, the basis weight on the reel is approximately 9 to 50 g / m ２and the basis weight becomes larger than the basis weight on the Yankee dryer. The crepe ratio based on the speed difference between the Yankee dryer and the reel is defined by the following formula: Crepe ratio (%) = 100 × (Yankee dryer speed (m / min) - reel speed (m / min)) ÷ reel speed (m / min) The quality of the crepe and the operability of creping are largely determined by the crepe ratio, and in the present invention, a crepe ratio in the range of 10 to 50% is suitable.

[0020] In the present invention, low-basis weight paper that has undergone a drying process is used as the cellulose raw material, and the pretreatment method for feeding it to the kneader is not particularly limited. Furthermore, pretreatment can be performed by either dry or wet crushing, with wet crushing being preferred. Wet crushing, i.e., in the form of a hydrated sheet, enables the paper to be crushed to uniform size, facilitating subsequent mixing with the thermoplastic resin and feeding the low-basis weight paper to the kneader. Furthermore, it facilitates uniform dispersion in the thermoplastic resin and defibration of the cellulose fibers to nano-levels in the kneader. Uniform dispersion and defibration further improve mechanical strength and impact strength and reduce the linear expansion coefficient. Known crushing methods can be used, including jet mills, roll mills, ball mills, cutter mills, stone mills, impact mills, Dyno Mills, ultrasonic mills, vibration mills, Loedige mixers, Henschel mixers, household juicer mixers, and mortars.

[0021] The cellulose fibers used in the present invention may also be subjected to a modification treatment to impart hydrophobicity. Known methods for imparting hydrophobicity include (1) directly hydrophobizing cellulose fibers by subjecting hydroxyl groups of cellulose to etherification, esterification, dithioesterification, or other reactions to introduce various hydrocarbon groups, and (2) indirectly hydrophobizing cellulose fibers by introducing ionic functional groups such as carboxyl groups, phosphate groups, phosphite groups, and amino groups into hydroxyl groups of cellulose through oxidation, etherification, esterification, carbamate conversion, or other reactions, and then introducing various hydrocarbon groups to these groups through direct ionic bonds, ionic bonds via metal ions, or covalent bonds such as amide bonds and ester bonds. While these hydrophobic treatments improve dispersibility in resin composites and various physical properties such as mechanical strength, they also raise concerns about reduced crystallinity, increased processing steps, and VOC emissions from residual compounds used in the modification treatment.

[0022] In the present invention, the effect is achieved without using these modified cellulose fibers, but in order to adjust the physical properties, cellulose fibers derived from low basis weight paper that has been subjected to a drying process may be modified and used.

[0023] In the present invention, high-basis weight paper other than low-basis weight paper that has undergone a drying process for cellulose fibers, and pulp that has been dried without a papermaking process can be used within a range that does not impair the effects of the present invention, but in order to suppress agglomerations in the resin composite, paper that does not include a coating layer, lamination, etc. is preferred. The blending ratio can be up to 49% by mass of the total cellulose fibers, but 33% by mass or less is preferred.

[0024] In the present invention, low basis weight paper that has undergone a drying process may be subjected to a pulverization process. Alternatively, low basis weight paper that has undergone a drying process may be hydrolytically crushed and then pulverized. By performing the pulverization process, the ease of conveyance during the production of a resin composite is improved, and agglomerates derived from cellulose fibers in the resin composite are suppressed, resulting in a resin composite with good physical properties. In the present invention, pulverization refers to a process in which a strong cutting force is applied to finely pulverize particles to the level of primary particles, and is clearly distinguished from disintegration (coarsely crushing low basis weight paper to the level of secondary agglomerates for the purpose of loosening the paper), which will be described later.

[0025] The method for carrying out the pulverization treatment is not particularly limited, but for example, the pulverization treatment can be carried out using a pulverizer, such as a dry pulverizer or a wet pulverizer.

[0026] Examples of dry grinding machines include cutting mills, impact mills, airflow mills, and media mills. These may be used alone or in combination, or multiple machines of the same model may be used in several stages.

[0027] Examples of cutting-type mills include Mesh Mill (manufactured by HORAI Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuma Seisakusho Co., Ltd.), Knife Mill (manufactured by Parman Co., Ltd.), Granulator (manufactured by Herbolt Co., Ltd.), and Rotary Cutter Mill (manufactured by Nara Machinery Works Co., Ltd.).

[0028] Examples of impact mills include Pulperizer (manufactured by Hosokawa Micron Corporation), Fine Impact Mill (manufactured by Hosokawa Micron Corporation), Super Micron Mill (manufactured by Hosokawa Micron Corporation), Sample Mill (manufactured by Seishin Corporation), Bantam Mill (manufactured by Seishin Corporation), Atomizer (manufactured by Seishin Corporation), Tornado Mill (Nikkiso Co., Ltd.), Turbo Mill (Turbo Kogyo Co., Ltd.), and Bevel Impactor (Aikawa Iron Works Co., Ltd.).

[0029] Examples of airflow mills include a CGS-type jet mill (manufactured by Mitsui Mining Co., Ltd.), a jet mill (manufactured by Sansho Industry Co., Ltd.), an Ebara Jet Micronizer (manufactured by Ebara Corporation), a Selenium Mirror (manufactured by Masuko Sangyo Co., Ltd.), and a supersonic jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.). Examples of media mills include a vibration ball mill.

[0030] Examples of wet mills include a Masscolloider (manufactured by Masuko Sangyo Co., Ltd.), a high-pressure homogenizer (manufactured by Sanmaru Kikai Kogyo Co., Ltd.), and a media mill. Examples of media mills include a bead mill (manufactured by Imex Co., Ltd.).

[0031] The loose bulk density of the pulverized material obtained through the pulverization process is preferably in the range of 10 to 60 g / L, more preferably 10 to 40 g / L, and even more preferably 10 to 30 g / L. Here, the loose bulk density can be measured, for example, by the following method. To eliminate fiber aggregation, approximately 50 g of the pulverized material was placed in a prepared bag, air was blown into it to break it up (30 seconds), and the pulverized material was dropped into a 1000 cc measuring cylinder up to 700 cc, and the weight was measured. The above operation was performed three times, and the average of the measured weights was taken as the loose bulk density. By having the loose bulk density in the above range, it is possible to prevent the pulverized material from clumping during transportation when producing a resin composite, and it is possible to make it easier to fill the resin composite with cellulose fibers uniformly and evenly.

[0032] Furthermore, the compacted bulk density of the pulverized material after the pulverization process is preferably in the range of 15 to 80 g / L, more preferably 15 to 60 g / L, and even more preferably 15 to 50 g / L. Here, the compacted bulk density can be measured, for example, by the following method. To eliminate fiber aggregation, approximately 50 g of the pulverized material was placed in a prepared bag, and air was blown into it to break it up (30 seconds). The pulverized material was then dropped into a 1000 cc graduated cylinder up to 1200 cc (approximately twice the measured volume, up to the limit where there are no graduations). The graduated cylinder was then fixed in mid-air, and the bottom was tapped with the palm of a hand 150 times at a rate of 250 times per minute. The pulverized material was then removed up to the 600 cc graduation on the graduated cylinder, and its weight was measured. The above procedure was repeated three times, and the average of the measured weights was taken as the compacted bulk density. By having the compacted bulk density within the above range, it is possible to prevent the pulverized material from forming lumps during transportation when pressure is applied to the pulverized material during production of the resin composite, and it is possible to make it easier for the cellulose fibers to be filled uniformly and without unevenness when the resin composite is made.

[0033] Furthermore, for the pulverized product that has undergone the pulverization process, the aspect ratio retention, expressed as (aspect ratio of the cellulose fibers in the pulverized product) / (aspect ratio of the cellulose fibers before the pulverization process) × 100, is preferably 60% or more, with the upper limit being 100% or less, preferably 99% or less, more preferably 95% or less, and even more preferably 93% or less. Here, the aspect ratio can be calculated by (fiber length of the cellulose fibers in the pulverized product) / (fiber diameter of the cellulose fibers in the pulverized product), and the fiber length and fiber diameter can be determined, for example, by measuring with a fiber tester. In the present invention, which includes a pulverization process, adjusting the aspect ratio retention within the above range can suppress decreases in mechanical strength, impact strength, linear expansion coefficient, etc., due to shortening of the cellulose fibers, making it easier to achieve the objects of the present invention.

[0034] (Thermoplastic Resin) The thermoplastic resin used in the present invention is preferably a resin having an impact strength of a predetermined value or more (for example, 10 kJ / m in the case of polyolefin) when used alone or in a resin mixture not containing cellulose fibers. ２ or more, in the case of polyamide or aliphatic polyester, 3.0 kJ / m ２ The resin is not particularly limited as long as it is such a resin, and preferred examples include polyamide, polyolefin, aliphatic polyester, aromatic polyester, polyacetal, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin), polycarbonate-ABS alloy (PC-ABS alloy), and modified polyphenylene ether (m-PPE).

[0035] These thermoplastic resins may also be chemically treated, for example, by acid modification or chlorination.

[0036] As the polyamide (PA), polyamide 6 (nylon 6, PA6), polyamide 66 (nylon 66, PA66), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 46, polyamide XD10 (PAXD10), polyamide MXD6 (PAMXD6), etc. can be preferably used.

[0037] As the polyolefin, polypropylene (PP), polyethylene (PE, (HDPE, MDPE, LDPE)), copolymers of ethylene and propylene, etc. can be preferably used. In addition, polyisobutylene, polyisoprene, polybutadiene, etc. can also be preferably used.

[0038] As polypropylene (PP), isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), etc. can be preferably used.

[0039] As the aliphatic polyester, polymers or copolymers of diols and aliphatic dicarboxylic acids such as succinic acid or valeric acid (for example, polybutylene succinate (PBS)), polyhydroxyalkanoates derived from microorganisms (for example, copolymers of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBH)), homopolymers or copolymers of hydroxycarboxylic acids such as glycolic acid or lactic acid (for example, polylactic acid (PLA), poly ε-caprolactone (PCL), etc.), and copolymers of diols, aliphatic dicarboxylic acids, and the above-mentioned hydroxycarboxylic acids can be preferably used.

[0040] As the aromatic polyester, a polymer of a diol such as ethylene glycol, propylene glycol, or 1,4-butanediol with an aromatic dicarboxylic acid such as terephthalic acid can be preferably used. Specifically, for example, polyethylene terephthalate (PET), polypropylene terephthalate (PPT), or polybutylene terephthalate (PBT) can be preferably used.

[0041] As polyacetal (also called polyoxymethylene, POM), in addition to a homopolymer of paraformaldehyde, a copolymer of paraformaldehyde and oxyethylene can also be preferably used.

[0042] As the polycarbonate (PC), a reaction product of bisphenol A or a bisphenol derivative thereof with phosgene or phenyl dicarbonate can be preferably used.

[0043] As polystyrene (PS), in addition to general-purpose PS (GPPS), PS (HIPS) in which a rubber component is dispersed in a PS matrix to improve impact resistance, and styrene copolymers (acrylonitrile-butadiene-styrene copolymers, ABS resins) can be suitably used.

[0044] PC-ABS alloys are suitable for use because of their excellent impact resistance, weather resistance, and moldability. As m-PPE, blends of PPE and PS (PPE-PS blends) are suitable for use because of their high heat resistance and light weight.

[0045] Furthermore, examples of thermoplastic resins that can be used other than those mentioned above include polyvinyl chloride, polyvinylidene chloride, fluororesins, (meth)acrylic resins, (thermoplastic) polyurethanes, vinyl ether resins, polysulfone resins, cellulose resins (e.g., triacetylated cellulose, diacetylated cellulose, acetylbutyl cellulose, etc.), copolymers of polystyrene and acrylonitrile (AS resins), biodegradable resins other than those mentioned above, such as PHA, PBSA, and PBAT, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyamideimide, polyetherimide, polyetherketone, polyimide, liquid crystal polymers, and fluororesins.

[0046] These thermoplastic resins preferably have impact strengths of a predetermined value or more when blended together or as a single thermoplastic resin, and may be copolymers of the respective thermoplastic resins. While there are no particular limitations on the copolymers, it is preferable to use polyolefins such as polyethylene, polypropylene, and polybutene, polyamide 6 (nylon 6, PA6), polylactic acid (PLA), etc., from the viewpoint of readily exhibiting impact strength. When polyolefins are used as the thermoplastic resin, the impact strength should be 10 kJ / m or more. ２ When polyamide 6 (nylon 6, PA6) or polylactic acid (PLA) is used as the thermoplastic resin, the impact strength is 3.0 kJ / m ２ Furthermore, when the impact strength of the base resin itself is low, the impact strength of the entire thermoplastic resin is preferably a predetermined value or more (for example, 10 kJ / m in the case of an elastomer containing polyolefin) by blending the elastomer described below. ２ or more, in the case of an elastomer containing polyamide or aliphatic polyester, 3.0 kJ / m ２ or more).

[0047] In the present invention, the following materials can be used as the elastomer: for example, natural rubber, chloroprene rubber, ethylene-propylene-non-conjugated diene copolymer rubber, ethylene-butene-1 copolymer rubber, ethylene-hexene copolymer rubber, ethylene-octene copolymer rubber, polybutadiene, styrene-butadiene block copolymer rubber, styrene-butadiene copolymer rubber, partially hydrogenated styrene-butadiene-styrene block copolymer rubber, styrene-isoprene block copolymer rubber, partially hydrogenated styrene-isoprene block copolymer rubber, polyurethane rubber, styrene graft-ethylene-propylene Examples of suitable elastomers include styrene-non-conjugated diene copolymer rubber, styrene-graft-ethylene-propylene copolymer rubber, styrene / acrylonitrile-graft-ethylene-propylene-non-conjugated diene copolymer rubber, styrene / acrylonitrile-graft-ethylene-propylene-non-conjugated diene copolymer rubber, chlorosulfonated polyethylene rubber, silicone rubber, ethylene-vinyl acetate rubber, epichlorohydrin rubber, polysulfide rubber, metallocene-catalyzed polyethylene, and metallocene-catalyzed ethylene-propylene-non-conjugated diene copolymer rubber. These elastomers can be used alone or in combination of two or more. Rubbers that can be used in liquid form, such as latex rubber, can also be used.

[0048] In the present invention, when an elastomer is added to a resin, the amount of the elastomer added is preferably within a range that does not impair the properties of the thermoplastic resin, i.e., the relationship between mechanical strength, impact strength, and linear expansion coefficient. The amount is preferably 50% by mass or less, and more preferably 30% by mass or less, of the resin composite, but is preferably 8% by mass or more, and even more preferably 13% by mass or more. If the amount added is too high, the improvement in mechanical strength is small, and if the amount added is too low, the improvement in impact strength is small. The elastomer may be added alone with the thermoplastic resin during the heat-kneading process described below, or may be added in advance as a thermoplastic resin-elastomer blend.

[0049] In the present invention, a compatibilizing resin may be added together with the cellulose fibers and thermoplastic resin. The compatibilizing resin functions to improve the uniform mixing and adhesion between the cellulose fibers and the thermoplastic resin. Examples of compatibilizing resins that can be used in the present invention include polymer resins having a low-molecular-weight dicarboxylic acid capable of forming an acid anhydride, such as carboxylic acid, maleic acid, succinic acid, or glutaric acid, on the polyolefin chain, such as polypropylene or polyethylene; polymer resins having a primary amine, secondary amine, or amide on the polyolefin chain, such as polypropylene or polyethylene; and polymer resins having a silanol group on the polyolefin chain, such as polypropylene or polyethylene. However, when using a polyolefin resin, for example, it is preferable to use a resin mainly composed of maleic anhydride-modified polypropylene (MAPP) or maleic anhydride-modified polyethylene (MAPE), to which maleic acid, which easily interacts with the hydroxyl groups of cellulose, has been added.

[0050] The amount of the compatibilizing resin having the above characteristics added is preferably 5 to 100% by mass, more preferably 10 to 50% by mass, based on the amount of cellulose. If the amount added exceeds 100% by mass, the compatibilizing resins will self-aggregate, and the effects of the present invention will not be achieved.

[0051] The compatibilizing resin may be used alone or as a mixture of two or more types. When used as a graft material of one or more polymers and polyolefin, the base resin constituting the graft material is not particularly limited, but polyethylene, polypropylene, polybutene, etc. can be used from the viewpoint of ease of production of the graft material.

[0052] The thermoplastic resin used in the present invention preferably has an impact strength of at least a predetermined value. Specifically, when a polyolefin is used as the thermoplastic resin, the impact strength is preferably 10 kJ / m or more. ２ More preferably, 18 kJ / m ２ When polyamide 6 (nylon 6, PA6) is used as the thermoplastic resin, the impact strength is preferably 3.0 kJ / m ２ More preferably, 4.0 kJ / m ２When polylactic acid (PLA) is used as the thermoplastic resin, the impact strength is 3.0 kJ / m ２ More preferably, 4.0 kJ / m ２ Preferably, the impact strength in the present invention is a value measured by an Izod impact test (ISO 180) or a Charpy impact strength test (ISO 179-1). For example, an Izod impact test can be performed by preparing a rectangular test piece (10 mm x 80 mm x 4 mm) of a thermoplastic resin or a thermoplastic resin-elastomer blend using an injection molding machine and using an Izod impact tester (manufactured by Toyo Seiki Seisakusho, Ltd.). Specifically, a notch with a depth of 2 mm is formed in the center of the test piece, and the notch side is struck with a hammer of appropriate energy to propagate a crack from the notch, and the impact strength can be calculated. A higher impact strength value indicates better impact strength.

[0053] The impact strength of a thermoplastic resin can be determined by measuring a resin composite blended with components other than cellulose fiber. If the impact strength of the resin or elastomer used is known, the impact strength can be determined by taking the weighted average of the impact strength values ​​of the major thermoplastic resins that account for 67% or more by mass of the thermoplastic resin.

[0054] Furthermore, in the present invention, depending on various applications, fillers other than cellulose fiber may be used in combination, such as mineral fillers such as talc, calcium carbonate, titanium oxide, glass beads, etc., and fiber fillers such as whiskers, glass fiber, carbon fiber, aramid fiber, carbon nanotubes, etc. The content is not particularly limited as long as the effects of the present invention are not impaired, but for example, 0.01 to 10 mass % in the resin composite is preferred.

[0055] The resin composite of the present invention may contain optional additives, as needed, in addition to the thermoplastic resin or blend of a thermoplastic resin and an elastomer, and cellulose fibers. Examples of optional additives include low-molecular-weight compatibilizers, surfactants, starches, polysaccharides such as alginic acid, natural proteins such as gelatin, glue, and casein, inorganic compounds such as tannin, zeolite, ceramics, and metal powder, viscosity modifiers, colorants, plasticizers, pigments, dyes, antistatic agents, UV absorbers, antioxidants, light stabilizers, and flame retardants. The content of the optional additives is not particularly limited as long as the effects of the present invention are not impaired. For example, a content of 0.01 to 10% by mass of the resin composite is preferred.

[0056] (Production of Resin Composite) The resin composite of the present invention can be obtained by heating and kneading the above-mentioned thermoplastic resin, cellulose fibers, and any additives used as needed.

[0057] To achieve the expected effects of the present invention, it is important that the resin composite is uniformly and evenly filled with an amount of cellulose fiber appropriate for the target thermoplastic resin, resulting in a uniform structure and close packing with reduced structural defects. Therefore, the blending ratio of thermoplastic resin to cellulose fiber is not uniformly determined because it depends on the impact strength of the thermoplastic resin used and the degree of fiber defibration. However, for example, by nano-sizing the entire cellulose fiber, it can be effective with a small amount added, while even if the defibration is not very strong, impact strength can be improved by adding sufficient cellulose fiber. The blending ratio of thermoplastic resin to cellulose fiber can be produced at a mass ratio of 97:3 to 20:80 in the resin composite, preferably 89:11 to 40:60, and more preferably 87:13 to 49:51, which allows for the production of resin composites with excellent mechanical strength, impact strength, and linear expansion coefficient. Furthermore, even if the cellulose is not defibrated to the nano-level, the effect is still exhibited if the cellulose fiber content in the resin composite is 16% by mass or more, and even more so if it is 21% by mass or more. A cellulose fiber content of more than 51% by mass is undesirable because it reduces fluidity during molding, reduces moldability, and causes various molding defects. However, since a high cellulose fiber content increases convenience and economy during transportation, when used as a cellulose fiber masterbatch for the present invention, a high cellulose content of 51% or more may be used. It has also been found that the use of a thermoplastic resin with high impact strength improves impact strength even with the same amount of cellulose fiber added, making it possible to adjust the balance between the mechanical properties, impact strength, and linear expansion coefficient that are ultimately required.

[0058] The heating temperature can be adjusted according to the melting point of the thermoplastic resin used. The heating temperature is preferably about ±10°C of the minimum processing temperature recommended by the thermoplastic resin supplier. By setting the heating temperature within this temperature range, the thermoplastic resin, cellulose fiber, and any optional additives can be uniformly mixed.

[0059] The heating and kneading time can be adjusted within the range recommended by the kneader manufacturer, taking into account the production volume, by adjusting the equipment performance, rotation speed, and other operating conditions. A shorter heating time is preferable because it can prevent deterioration due to heat and oxidation during heating and kneading, but if the heating time is too short, there is a risk of insufficient dispersion in the resin. Therefore, when heating and kneading, it is preferable to include a structure that strengthens kneading, such as a rotor or kneader, in the screw piece, and in particular, using rotors in multiple locations is even more preferable, as it can promote nano-fibrillation.

[0060] In order to prevent deterioration due to heating and oxidation during the heat kneading, it is preferable to add an additive such as an antioxidant and to carry out the kneading in a nitrogen atmosphere.

[0061] As the kneader, a single-screw or multi-screw kneader can be used, but a twin-screw kneader is preferred.

[0062] In the present invention, the thermoplastic resin, cellulose fiber, and optional additives may be fed to the kneader all at once or in multiple batches. When feeding multiple batches, a side feeder or the like may be used.

[0063] There is no particular limit to the number of times the treatment is carried out in a kneader to obtain a resin composite. In the case of multiple treatments, the same material may be kneaded multiple times. In the case of multiple treatments, the cellulose fiber content may be produced at a high concentration of 30 to 80% in the first treatment, and with each treatment, thermoplastic resin, cellulose fiber, and any additives used as needed may be added so that the resin composite finally obtained falls within the range of the present invention.

[0064] The cellulose fibers used in the present invention can be any of the following: low-basis weight paper that has been subjected to a drying process and then dry-pulverized; paper that has been wet-pulverized in a moist state before being pulverized; and paper that has been moistened after dry-pulverization. When used in a dry state, this is economical because existing equipment for general resin kneading can be used, but when used in a moist state, nano-fibrillation is promoted during kneading, allowing for the production of higher quality resin composites.

[0065] It is also possible to mix the thermoplastic resin and cellulose fibers in advance before heat-kneading them. For example, (i) crushed low-basis weight paper that has been dried in a dry state can be mixed with a thermoplastic resin, and the resulting mixture can be supplied to a kneader. Alternatively, (ii) crushed low-basis weight paper that has been dried and powdered or granular thermoplastic resin can be dispersed in a dispersion liquid in which they are insoluble, mixed, and then dried and supplied to a kneader. Examples of mixing methods in this case include bench rolls, Banbury mixers, kneaders, planetary mixers, Loedige mixers, Henschel mixers, bladed mixers, and revolutionary or rotational mixers.

[0066] In the case of (i) above, it is also possible to add any additives when pre-mixing the crushed low basis weight paper that has been subjected to the drying process with the powdered or granular thermoplastic resin before heating and kneading.

[0067] (Molded article) The resin composite of the present invention can be used as a molded article processed into a desired shape. When producing a molded article, the resin composite of the present invention can be processed into various shapes such as pellets, flakes, powder, sheet, plate, film, etc., and used as a molding material.

[0068] Examples of molding methods include injection molding, mold molding, extrusion molding, blow molding, vacuum / pressure molding, and molding using a 3D printer. It is also possible to carry out molding involving physical or chemical foaming. Examples of the shape of the molded article include sheet, plate, film, and three-dimensional structure. Molded articles of various shapes can be produced by the above molding method depending on the application. By using the resin composite of the present invention, molded articles excellent in mechanical strength (flexural modulus, flexural strength), impact strength, and linear expansion coefficient can be obtained. That is, when the thermoplastic resin used is polyolefin, for example, a molded article having a flexural modulus of 1.0 GPa or more and an impact strength of 5.0 kJ / m ２ or more, and the linear expansion coefficient is 100×10 －６In addition, when the thermoplastic resin used is nylon 6 (PA6), for example, a molded article having a flexural modulus of 1.60 GPa or more and an impact strength of 2.0 kJ / m or less can be obtained. ２ or more, and the linear expansion coefficient is 70 × 10 －６ In addition, when the thermoplastic resin used is polylactic acid (PLA), for example, a molded article having a flexural modulus of 3.50 GPa or more and an impact strength of 3.0 kJ / m or less can be obtained. ２ or more, and the linear expansion coefficient is 80×10 －６ / K or less.

[0069] That is, when the thermoplastic resin used is polyolefin, the resin composite of the present invention obtained as described above and the molded article obtained from the resin composite of the present invention have a flexural modulus of 1.00 GPa or more and an impact strength of 5.0 kJ / m ２ or more, and the linear expansion coefficient is 100×10 －６ / K or less, the flexural modulus is 1.6 GPa or more, and the impact strength is 9.5 kJ / m ２ or more, and the linear expansion coefficient is 60×10 －６ / K or less, and the flexural modulus is 1.8 GPa or more and the impact strength is 10.0 kJ / m ２ or more, and the linear expansion coefficient is 50×10 －６ / K or less, and the flexural modulus is 2.0 GPa or more and the impact strength is 10.5 kJ / m ２ or more, and the linear expansion coefficient is 40×10 －６ / K or less. In addition, the bending strength is preferably 25 MPa or more, more preferably 30 MPa or more, and even more preferably 35 MPa or more. The specific gravity is preferably less than 1.4.

[0070] Furthermore, when the thermoplastic resin used is nylon 6 (PA6), the resin composite of the present invention obtained as described above and the molded article obtained from the resin composite of the present invention have a flexural modulus of 1.60 GPa or more and an impact strength of 2.0 kJ / m ２ or more, and the linear expansion coefficient is 70 × 10 －６ / K or less, the flexural modulus is 3.00 GPa or more, and the impact strength is 2.0 kJ / m ２ or more, and the linear expansion coefficient is 70 × 10 －６ / K or less. In addition, the bending strength is preferably 90 MPa or more, and more preferably 100 MPa or more. The specific gravity is preferably less than 1.4.

[0071] Furthermore, when the thermoplastic resin used is polylactic acid (PLA), the resin composite of the present invention obtained as described above and the molded article obtained from the resin composite of the present invention have a flexural modulus of 3.50 GPa or more and an impact strength of 3.0 kJ / m ２ or more, and the linear expansion coefficient is 80×10 －６ / K or less, the flexural modulus is 4.00 GPa or more, and the impact strength is 3.05 kJ / m ２ or more, and the linear expansion coefficient is 70 × 10 －６ / K or less. In addition, the bending strength is preferably 105 MPa or more. The specific gravity is preferably less than 1.4.

[0072] The flexural modulus and flexural strength can be measured, for example, as follows. Specifically, rectangular test specimens (10 mm x 80 mm x 4 mm) are prepared using the resin composite of the present invention using an injection molding machine (Nissei Plastic Industrial Co., Ltd., NPX 7 model, clamping force 7 tons). Specifically, the cylinder temperature of the injection molding machine is set to 170°C (feeding section) to 190°C (metering section) to melt the resin composite, and then injected into a mold at a temperature of 35°C to prepare a molded body. The obtained test specimens are left to stand for one day in an atmosphere of 23°C and 50% relative humidity, and then tested using the following test method. For example, a strength test is performed on the test specimens using a universal testing machine (Shimadzu Corporation, AG5000E model) under test conditions of a support distance of 64 mm and a test speed of 10 mm / min, and the flexural modulus and flexural strength are determined. For both the flexural modulus and flexural strength, higher values ​​indicate better mechanical strength.

[0073] The impact strength is a value measured by an Izod impact test (ISO 180) or a Charpy impact strength test (ISO 179-1). For example, an Izod impact test can be performed by preparing a rectangular test piece (10 mm x 80 mm x 4 mm) of the resin composite of the present invention using an injection molding machine and using an Izod impact tester (manufactured by Toyo Seiki Seisakusho, Ltd.). Specifically, a notch with a depth of 2 mm is formed in the center of the test piece, and the notch side is struck with a hammer of appropriate energy to propagate a crack from the notch, and the impact strength can be calculated. A higher impact strength value indicates better impact strength.

[0074] The linear expansion coefficient is the linear expansion coefficient between 30 and 50°C, which is the temperature range in which PP-based materials often have the largest linear expansion coefficient when the resin composite of the present invention is heated from 0°C to 100°C, and can be measured under the conditions specified in ASTM D696. A smaller measured linear expansion coefficient indicates better dimensional stability.

[0075] The specific gravity can be measured by a gas displacement method using AccuPyc II manufactured by Micromeritics.

[0076] The molded article produced from the resin composite of the present invention can be used in fields requiring mechanical strength, impact strength, and a linear expansion coefficient. Specifically, it can be used for interior, exterior, and structural materials for transportation equipment such as automobiles, trains, ships, and airplanes; housings, structural materials, and internal parts for electrical appliances such as personal computers, televisions, telephones, and watches; housings, structural materials, and internal parts for mobile communication devices such as mobile phones; housings, structural materials, and internal parts for portable music players, video players, printers, copiers, sporting goods, and the like; building materials; office equipment such as stationery, and containers.

[0077] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, "parts" are based on mass unless otherwise specified.

[0078] <Measurement and Evaluation Methods> In the examples and comparative examples, measurements and evaluations were carried out as follows.

[0079] (Measurement of paper basis weight) Measurement of the basis weight of the paper used in the examples and comparative examples was measured using the following method. The paper, the area of ​​which had been measured in advance, was dried overnight in an oven at 105°C, and then left to stand for 30 minutes in a desiccator containing a sufficient amount of silica gel, after which the mass was measured. The measured mass was divided by the area to calculate the basis weight.

[0080] (Mechanical Strength Test (Three-Point Bending Test)) - Manufacturing Method of Test Piece (Molded Article) Using the resin composites obtained in the Examples and Comparative Examples, rectangular test pieces (10 mm x 80 mm x 4 mm) were produced using an injection molding machine (Nissei Plastic Industrial Co., Ltd., NPX7 model, mold clamping force 7 tons). Specifically, the cylinder temperature of the injection molding machine was set to 170°C (feeding section) to 190°C (metering section) to melt the resin composite, and the resin composite was injected into a mold at a temperature of 35°C to prepare a molded article. The obtained test pieces were left to stand for one day in an atmosphere at a temperature of 23°C and a relative humidity of 50%, and then tested.

[0081] Test method: A strength test was performed on the test specimens using a universal testing machine (Shimadzu Corporation, AG5000E model). The test conditions were a support distance of 64 mm and a test speed of 10 mm / min, and the flexural modulus and flexural strength were determined. For both the flexural modulus and flexural strength, the higher the values, the better the mechanical strength.

[0082] (Izod Impact Test) Using the resin composites obtained in the Examples and Comparative Examples, rectangular test pieces (10 mm x 80 mm x 4 mm) were prepared using an injection molding machine (Nissei Plastic Industrial Co., Ltd., NPX7 model, mold clamping force 7 tons), and an Izod impact test was performed using an Izod impact tester (Toyo Seiki Seisakusho Co., Ltd.). Specifically, a 2 mm deep notch was formed in the center of the test piece. A hammer with appropriate energy was used to strike the notch side, causing a crack to propagate from the notch, and the impact strength was calculated. A higher value indicates better impact strength. Izod impact tests were also performed on thermoplastic resins containing no cellulose fiber or blends of thermoplastic resins and elastomers used in the production of the resin composites.

[0083] (Linear expansion coefficient) This is the linear expansion coefficient (also called linear thermal expansion coefficient) between 30 and 50°C, which is the temperature range in which PP-based materials often have the largest linear thermal expansion coefficient when the sample is heated from 0°C to 100°C, and was measured under the conditions specified in ASTM D696. A smaller value indicates better dimensional stability.

[0084] (Specific Gravity) The specific gravity was measured by a gas displacement method using AccuPyc II manufactured by Micromeritics.

[0085] (Loose bulk density) In order to eliminate fiber aggregation, about 50 g of the above-mentioned pulverized material was placed in a prepared bag, and air was blown into it to break it up (30 seconds), and the pulverized material was dropped into a 1000 cc measuring cylinder up to 700 cc, and the weight was measured. The above operation was performed three times, and the average value of the measured weight was taken as the loose bulk density.

[0086] (Packing Bulk Density) To eliminate fiber aggregation, approximately 50 g of the above-mentioned pulverized material was placed in a prepared bag, and air was blown into it to break it up (30 seconds). The pulverized material was then dropped into a 1000 cc measuring cylinder up to 1200 cc (approximately twice the measured amount, up to the limit where there are no markings). The measuring cylinder was then fixed in the air, and the bottom was tapped with the palm of a hand 150 times at a rate of 250 times per minute. The pulverized material was then removed up to the 600 cc mark on the measuring cylinder, and the weight was measured. The above procedure was repeated three times, and the average of the measured weights was taken as the packing bulk density.

[0087] (Fiber Length, Fiber Diameter, and Aspect Ratio) The fiber length and fiber diameter were measured using a fiber tester (L&W Fiber Tester Plus (manufactured by Lorentzen & Wettre)). The aspect ratio was calculated by (fiber length) / (fiber diameter).

[0088] (Cellulose fiber transportability) The cellulose fibers obtained in the examples and comparative examples were fed into a feeder through a raw material inlet using a twin-screw kneader (manufactured by Technovel Co., Ltd., screw diameter φ15 mm, L / D 45 (L / D is the ratio of screw length L to screw diameter D)) equipped with a feeder. The horizontal transportability of the cellulose fibers was visually observed when the feeder was operated at a flow rate of 0.06 kg / h. Furthermore, the cellulose fibers transported to the reaction section were fed into the top of the screw, and the cellulose fiber feeding operation during operation at a screw rotation speed of 200 rpm was also visually observed and evaluated according to the following criteria. ◯: In visual observation for 10 minutes, no clogging of the cellulose fibers occurred in either the feeder transportability or the feeding operation in the reaction section, and the transportability was good. ×: In visual observation for 10 minutes, clogging of the cellulose fibers was observed in either the feeder transportability or the feeding operation in the reaction section, and the transportability was poor.

[0089] <Production of Resin Composite> (Example 1) Toilet paper (Kleenex, manufactured by Nippon Paper Crecia Co., Ltd., basis weight 21 g / m) was used as cellulose fiber. ２ The roll-shaped product was pulverized using a pulverizer (UC-360, manufactured by Horai Co., Ltd.) with a screen diameter of φ2 mm to obtain pulverized product 1. 27 parts by dry mass of pulverized product 1 obtained by the pulverization treatment described above, 68 parts of polypropylene (PP; Prime Polypro J-466HP manufactured by Prime Polymer Co., Ltd.), and 5 parts of maleic anhydride-modified polypropylene (MAPP; Toyobo Co., Ltd., Toyo Tack H1000P) as a compatibilizing resin were added, and the mixture was stirred in a Henschel mixer to obtain a pulverized product.

[0090] Without drying, this disintegrated material was supplied to a twin-screw kneader (manufactured by Technovel Co., Ltd., screw diameter φ15 mm, L / D 45 (L / D is the ratio of screw length (L) to screw diameter (D)), rotors are used at three locations in the screw configuration) and subjected to heat kneading to obtain 100 parts of a resin composite. The cylinder temperature of the twin-screw kneader was 160°C. The impact strength of the thermoplastic resin containing no cellulose fiber was 80 kJ / m ２ It was.

[0091] The resin composite was used to prepare rectangular test pieces, which were subjected to a mechanical strength test, an Izod impact test, and measurement of the linear expansion coefficient. The results are shown in Table 1.

[0092] (Example 2) Pulverization was carried out in the same manner as in Example 1, except that the toilet paper used for pulverization was changed from roll-shaped toilet paper to crushed Henschel product, and crushed material 2 was obtained. Here, the crushed Henschel product was toilet paper (Kleenex, manufactured by Nippon Paper Crecia Co., Ltd., basis weight 21 g / m ２ ) was mixed in a Henschel mixer (FM150, manufactured by Nippon Coke & Engineering Co., Ltd.) at 20 m / s for 2 minutes, followed by two cycles of 2 minutes at 80 m / s. A resin composite was obtained in the same manner as in Example 1, except that crushed material 1 was replaced with crushed material 2. Strip-shaped test pieces were prepared using the resulting resin composite and subjected to mechanical strength testing, Izod impact testing, and linear expansion coefficient measurement. The results are shown in Table 1.

[0093] (Example 3) Pulverization was performed in the same manner as in Example 2, except that the screen diameter during pulverization was changed to φ20 mm, to obtain pulverized material 3. Furthermore, a resin composite was obtained in the same manner as in Example 2, except that pulverized material 2 was changed to pulverized material 3. Rectangular test pieces were prepared using the obtained resin composite and subjected to mechanical strength tests, Izod impact tests, and linear expansion coefficient measurements. The results are shown in Table 1.

[0094] Comparative Example 1 27 parts by dry weight of the above Henschel-shredded toilet paper was prepared, 68 parts of polypropylene (PP; Prime Polypro J-466HP manufactured by Prime Polymer Co., Ltd.) and 5 parts of maleic anhydride-modified polypropylene (MAPP; Toyobo Co., Ltd., Toyo Tack H1000P) as a compatibilizing resin were added, and the mixture was stirred in a Henschel mixer to obtain a shredded product. Note that no water was added.

[0095] Without drying, this crushed material was supplied to a twin-screw kneader (manufactured by Technovel Co., Ltd., screw diameter φ15 mm, L / D 45 (L / D is the ratio of screw length (L) to screw diameter (D)), rotors are used at three locations in the screw configuration) and subjected to heat kneading to obtain 100 parts of a resin composite. The cylinder temperature of the twin-screw kneader was 160°C. The impact strength of the thermoplastic resin containing no cellulose fiber was 80 kJ / m ２ It was.

[0096] The resin composite was used to prepare rectangular test pieces, which were subjected to a mechanical strength test, an Izod impact test, and measurement of the linear expansion coefficient. The results are shown in Table 1.

[0097]

[0098] As shown in Table 1, a resin composite containing a thermoplastic resin and cellulose fiber, in which the raw material of the main component of the cellulose fiber has a basis weight of 100 g / m2 after being subjected to a drying process. ２ The resin composite, which is a low basis weight paper described below, has excellent results in mechanical strength tests, Izod impact tests, and linear expansion coefficient measurements, and is also excellent in transportability, especially when the cellulose fibers are pulverized through a pulverization process.

Claims

1. A resin composite containing a thermoplastic resin and cellulose fibers, the main component of which is a raw material having a basis weight of 100 g / m2 after a drying process. ２ Resin composite, which is a low basis weight paper of:

2. The resin composite according to claim 1, wherein the cellulose fibers are pulverized through a pulverization process.

3. A resin composite according to claim 1 or 2, characterized in that the cellulose fibers are ground and have a loose bulk density in the range of 10 to 60 g / L.

4. A resin composite according to claim 1 or 2, characterized in that the cellulose fibers are ground and have a bulk density in the range of 15 to 80 g / L.

5. A resin composite according to claim 1 or 2, characterized in that the aspect ratio retention rate of the cellulose fibers, expressed as (aspect ratio of pulverized cellulose fibers) / (aspect ratio of cellulose fibers before the pulverization process) x 100 (%), is 60% or more.

6. The low-weight paper has a basis weight of 3 to 40 g / m ２ The resin composite according to claim 1 or 2, which is a tissue paper.

7. The resin composite of claim 1 or 2, wherein the low basis weight paper is household tissue paper.

8. The thermoplastic resin is a polyolefin or a blend of a polyolefin and an elastomer, and has a flexural modulus of 1.00 GPa or more and an impact strength of 5.0 kJ / m ２ or more, and the linear expansion coefficient is 100×10 －６ 3. The resin composite according to claim 1, wherein the viscosity is 0.1 to 1000 MPa.

9. The thermoplastic resin has an impact strength of 3.0 kJ / m ２ 3. The resin composite according to claim 1 or 2, which is a nylon or a blend of nylon and an elastomer.

10. The thermoplastic resin is nylon or a blend of nylon and elastomer, and has a flexural modulus of 1.60 GPa or more and an impact strength of 2.0 kJ / m ２ or more, and the linear expansion coefficient is 70×10 －６ 3. The resin composite according to claim 1, wherein the viscosity is 0.1 to 1000 MPa.

11. The thermoplastic resin has an impact strength of 3.0 kJ / m ２ 3. The resin composite according to claim 1 or 2, which is a blend of the above polylactic acid or polylactic acid with an elastomer.

12. The thermoplastic resin is polylactic acid or a blend of polylactic acid and elastomer, and has a flexural modulus of 3.50 GPa or more and an impact strength of 3.0 kJ / m ２ or more, and the linear expansion coefficient is 80×10 －６ 3. The resin composite according to claim 1, wherein the viscosity is 0.1 to 1000 MPa.

13. A method for producing a resin composite, comprising the following steps (A) to (C): Step (A): subjecting raw pulp to a papermaking step and a drying step, and producing a paper having a basis weight of 100 g / m ２ The steps for obtaining low basis weight paper are as follows: Step (B): A step of pulverizing the low basis weight paper that has been subjected to step (A); Step (C): A step of mixing the low basis weight paper pulverized in step (B) with a thermoplastic resin, and kneading the mixture under heating.

14. The method for producing a resin composite according to claim 13, wherein the step (B) comprises pulverizing the low basis weight paper so that the loose bulk density of the low basis weight paper is in the range of 10 to 60 g / L.

15. A method for producing a resin composite according to claim 13 or 14, characterized in that in step (B), the low basis weight paper is pulverized so that the hard bulk density of the low basis weight paper is in the range of 15 to 80 g / L.

16. A method for producing a resin composite as described in claim 13 or 14, characterized in that the process (B) comprises crushing the low basis weight paper so that the aspect ratio retention rate, expressed as (aspect ratio of the crushed low basis weight paper) / (aspect ratio of the low basis weight paper before the crushing process) x 100 (%), is 60% or more.

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